body,
html {
  width: 100%;
  height: 100%;
  padding: 0;
  margin: 0;
  overflow: hidden;
}
body {
  padding: 10px;
  box-sizing: border-box;
}
#modeBtn {
  font-size: 2rem;
  float: right;
  border: none;
  background: transparent;
}
.night {
  background-color: #000;
  color: #fff;
}
.light {
  background-color: #fff;
  color: #000;
}
